Left: zoom into δv_LSR from Fig. 8 toward the position of the protostar. The black contours mark the region of the blue streamer found in Sect. 4.2.1. The horizontal and vertical black lines show the positions of the horizontal and vertical cuts for the plots on the right. The black circle at the lower left corner represents the beam size of the NH₃ (1,1) observations. Right: horizontal and vertical cuts of HC₃N v_LSR and NH₃ v_LSR. The purple points with the purple area represent the HC₃N (10 − 9) v_LSR and its associated uncertainty after smoothing to reach the same resolution as the NH₃ (1,1) v_LSR. The green points represent the NH₃ (1,1) v_LSR (the uncertainties are roughly the size of the points). The black curves and black areas represent the difference between HC₃N (10 − 9) NH₃ (1,1) v_LSR. The blue areas represent the location covered by the blue streamer.